1. Field of the Invention
The present invention relates to a vehicular rear gate opening and closing apparatus whose upper end is pivotally connected with a vehicle body so as to swing up and down and more particularly to a rear gate capable of opening and closing in two ways by an actuator or by hand.
2. Discussion of Prior Art
As shown in FIG. 11, generally a rear gate 102 disposed in the rear of a vehicle is a lid swinging up and down for opening and closing an opening 101. The rear gate 102 is at the upper end thereof secured to a hinge arm 103 rotatably supported by an upper edge of the opening 101 of a vehicle body 100.
A gas stay 105 is connected between a side edge of the rear gate 102 and a side edge 104a of the opening 101 formed along a rear pillar 104. The gas stay 105 has a piston rod 105a biased in an axial (longitudinal) direction by sealed gas pressure. When the rear gate 102 opens or closes, the gas stay 105 expands or contracts according to an opening or closing angle of the rear gate 102 and the biasing force applies an assist force to the piston rod 105a, thereby an opening or closing effort of the rear gate 102 can be reduced.
According to a rear gate opening and closing mechanism disclosed in Japanese Patent Application Laid-open No. Toku-Kai-Hei 5-280242 and also shown in FIG. 12, the rear gate 112 has a hinge arm 113 at the upper end thereof and the hinge arm 113 is pivotally supported by a vehicle body 110. The hinge arm 113 has a curved section 114 formed in such a manner as extending forwardly from a pivoting point P of the hinge arm 113, making a U-turn and then extending backwardly. The curved section 114 communicates with a rear gate fitting section 115 to which the rear gate 112 is secured. A rod 116 is pivotally connected at a boss section 117 provided at the rear end thereof with a slightly lower part of the curved section 114 than the pivoting point P. A front end of the rod 116 is slidably fitted to a supporting hole 118 and a coil spring 119 is interposed between a rear spacer 120 and the boss section 117.
According to the rear gate structure shown in FIG. 11, the gas stay 105 laid between the rear gate 102 and the side edge 104a provides an assist force when the rear gate 102 operates to open or closed and as a result the operating effort of the rear gate 102 can be reduced.
Referring to FIG. 12, when the rear gate 112 is wings upward, the hinge arm 113 rotates integrally with the rear gate 112 around the pivoting point P. Then, since the coil spring 119 pushes the curved section 114, a rotating force is applied to the hinge arm 113, thereby the operating effort when opening the rear gate 112 can be reduced.
However, there is a fear that the gas stay 105 which is provided between the rear gate 102 and the side edge 104a hinders loading or unloading works through the opening 101. Further, since the gas stay 105 is exposed to the compartment, there is a problem that the interior space is limited as much and also there is an aethetic problem. To solve these problems, one idea is to accommodate the gas stay between the rear gate 102 and the side edge 104a of the opening 101. Since the diameter of the gas stay is determined by gas pressure for supporting the weight of the rear gate, the thickness of the pillar in which the gas stay is housed is dependant upon the rear gate. Further, since the stroke of the gas stay is determined by the specification of the rear gate, the straight portion of the rear pillar for accommodating the gas stay has an effect on the styling of the rear pillar itself. That is, the freedom of the rear design of the vehicle is restricted.
According to the rear gate structure disclosed by Toku-Kai-Hei 5-280242, when the rear gate 112 swings upward to open, the curved section 114 of the hinge arm 113 is pushed by the coil spring 119. As a result, the hinge arm 113 has a rotating force to reduce the operating effort of an operator. Further, since the gas stay is not disposed between the side edge of the opening and the rear gate 112, the freedom of designing of the rear pillar, the rear gate 112 and the like is enlarged.
On the other hand, the rear gate structure according to Toku-Kai-Hei 5-280242 is designed so as to open and close by lifting up or pushing down an outer handle of the rear gate by hand from outside of the vehicle. The opening and closing effort of the rear gate is generally troublesome to the operator and particularly, when it rains heavily and his or her hands are full with baggage, it is desirable that an opening and closing apparatus for automatically opening and closing the rear gate can be operated by the operator while he or she stays in the passenger compartment.